Examples of perpendicular lines

1. Are these straight lines perpendicular?

If the lines intersect at 90 degrees then they are perpendicular

The formula for each line is:

`y = 2x + 4`

And `y=-1/2x-1`

And ` y=mx+c` where m is the gradient

The test for perpendicular

`m_1\times\m_2=-1`

`2\times-1//2=?`

`2\times-1//2=-1`

Yes these lines are perpendicular.